Stacks of acids: Pentafluorobenzoic acid forms heterodimers with benzoic and 2,4,6-trimethylbenzoic that assemble into π stacks alternating phenyl pentafluorophenyl residues (see picture). Cocrystals these acids 1,4-bisarylbutadiynes contain homodimers sandwiched between the diacetylene molecules.

N-nitrosamines, whose chirality is solely due to hindered rotation about the N-N bond, are enantioselectively enclathrated by crystal host matrices of cholic or deoxycholic acid, as evidenced X-ray crystallography (see structure in picture) and CD spectra.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConformational Study of N-Nitroso-2,6-diphenylpiperidines and N-Nitroso-2,6-diphenylpiperidin-4-ones by Molecular Mechanics Calculations, X-ray Crystallography, 1H 13C NMR SpectroscopyMaria Gdaniec, Maria J. Milewska, Tadeusz Po-lonskiCite this: Org. Chem. 1995, 60, 23, 7411–7418Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November...

Several N-nitrosopiperidines with chirality solely due to a hindered rotation about the N−N bond were resolved enantiomers by inclusion crystallization optically active diols (TADDOLs). The absolute configuration of guest nitrosamines was deduced from X-ray crystal structures complexes. enclathrated liberated competitive complexation host piperazine. optical activity is manifested their CD spectra. A simple rule proposed for rationalization observed Cotton effect sign corresponding n−π*...

Several N-substituted maleimides containing substituents of varying bulkiness and polarity were synthesised tested for antimicrobial cytostatic activity. Neutral displayed relatively strong antifungal effect minimum inhibitory concentrations (MICs in the 0.5-4 µg ml(-1) range); their antibacterial activity was structure dependent all highly cytostatic, with IC(50) values below 0.1 ml(-1). Low but high noted basic tertiary aminoalkyl substituents. Chemical reactivity lipophilicity influenced...

Gestapelte Säuren: Pentafluorbenzoesäure bildet Heterodimere mit Benzoesäure und 2,4,6-Trimethylbenzoesäure, die sich zu π-Stapeln alternierenden Phenyl- Pentafluorphenylresten organisieren (siehe Bild). Mischkristalle dieser Säuren 1,4-Bisarylbutadiin-Derivaten enthalten Säure-Homodimere, zwischen den Diacetylenmolekülen sandwichartig eingelagert sind.

Cocrystals of seven star-shaped triaryl compounds with pentafluorophenol (pfp) were prepared and structurally characterized by the single-crystal X-ray diffraction method. Cocrystallization pfp planar (or almost planar) gave six 3:1 molecular complexes well-defined layered structures. The layers are composed alternating pfp3 trimers, linked hydrogen bonding, molecules held together in planes weak C–H···F interactions. Stacking interactions triaryl-substituted perfluorinated rings responsible...

Lactams can be obtained by the monothionation of imides with Lawesson’s reagent followed desulfurization resulted monothioimides Raney nickel.

The variable temperature (1)H, (13)C, and (19)F NMR spectra were measured for the title N-nitrosamines. observed unusually low N-N rotation barriers (12-15 kcal/mol) result from a significant deviation of nitrosamino system planarity. A pyramidal character amino nitrogen was confirmed by X-ray crystal structures two compounds bathochromic shifts n-pi absorption bands in UV spectra. nonplanarity moiety is due to strong pseudoallylic A((1,3)) strain caused steric interaction NNO group with...

The preparation and crystal structures of fourteen complexes N,N'-bis(2-pyridyl)aryldiamines with dicarboxylic acids two squaric acid are reported. recognition between the carboxylic 2-aminopyridine units occurs through formation cyclic R(2)2 (8) hydrogen bond motif, whereas creates analogous (9) motif. In 1:1 motifs generate infinite hydrogen-bonded 1D networks alternating component molecules. These further organised into densely packed layers assembled weaker C-H...O interactions. Analysis...

N 5-Acetyl-N 5-hydroxy-L-ornithine is obtained from L-ornithine in 20% overall yield via oxidation of the ω-amino group 2-benzyloxycarbonyl-L-ornithine tert-butyl ester with dibenzoyl peroxide and subsequent 5-acetylation.

Cocrystallization of N,N′-diaryloxalamides with pentafluorophenol (pfp) leads to 1 : 2 molecular complexes, which were characterized by X-ray crystallography. The non-planar oxalamide molecules and pfp assemble into polymeric tapes use the N–H⋯O O–H⋯O hydrogen bonds phenyl–perfluorophenyl interactions, whereas adopting planar conformations form flat trimers held together intermolecular creating two 7-membered rings.

Antifungal polyene macrolide antibiotics Amphotericin B (AmB) and Nystatin (NYS) were conjugated through the ω-amino acid linkers with diwalled "molecular umbrellas" composed of spermidine-linked deoxycholic or cholic acids. The presence "umbrella" substituents modulated biological properties antibiotics, especially their selective toxicity. Some AmB-umbrella conjugates demonstrated antifungal in vitro activity comparable to that mother antibiotic but diminished mammalian toxicity, hemolytic...

The LYS12 gene from Candida albicans, coding for homoisocitrate dehydrogenase was cloned and expressed as a His-tagged protein in Escherichia coli. purified product catalyzes the Mg2+- K+-dependent oxidative decarboxylation of to α-ketoadipate. recombinant enzyme demonstrates strict specificity homoisocitrate. SDS-PAGE CaHIcDH revealed its molecular mass 42.6 ± 1 kDa, whereas size-exclusion chromatography, eluted single peak corresponding 158 3 kDa. Native electrophoresis showed that may...

A three‐step procedure involving Diels–Alder condensation of maleic anhydride with furane, formation N ‐substituted imide upon reaction appropriate diamine, and a final retro regeneration the carbon–carbon double bond is proposed for an unequivocal synthesis basic maleimides. The novel method characterized by mild conditions, easy work‐up, high yields, no need additional catalysis.

T. Olszewska, M. J. Milewska, Połoński and Gdaniec, Chem. Commun., 1999, 1385 DOI: 10.1039/A901718F

The crystalline inclusion complexes of cholic acid with three symmetric N-aryl-N-nitrosamines were prepared, and their X-ray structures solved. As a result chiral conformations adopted by the enclathrated guest nitrosamines, solid-state CD spectra measured in KBr disks. observed Cotton effect sign, corresponding to n−π* transition, was correlated helicity twisted nitrosamine chromophore conjugated N-aryl substituent. In addition, absolute configuration enantiomorphous crystals...